Alternating-current electric bell



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QJ. ROHLAND ALTERNATING CURRENT ELECTRIC BELLA orign; Filed April 12. 1916 Il HQ Patented May 22, 1923.

UNHTED STATES Param ermee.

CURT J. ROHYLAND, 0F SEEKONK, MASSACHUSETTS-,vASSIGNOR, BY MESNE ASSIGN.- MENTS, TO SIGNAL ENGINEERING AND MANUFACTURING COMPANY, OF NEW YORK, N. Y., A CORPORATION OF MASSACHUSETTS.

ALTERNATING-CURRENT ELECTRIC BELL.

Application mea April 12, 1916, serial No. 90,757. Renewed octoberv e, 1922. serial Ne. 593,459.

To all @hom 'it may concern:

Be it known that I, CURT- J. RoriLeND, a citizen of the German Em ire, residln at Seekonk, in the county of ristol and tate' of Massachusetts, have invented 'ai new and useful Alternating-Current Electric Bell, of which the following is a specification..

.This invention relates to a sound producing device preferably in the form of a bell or gong, but also containing features suitable for application to a horn or the like, and it relates to a device of this k'ind intended to be operated solely by an alternating n iagnet.

The principal objects of this invention tuned, so to speakfsfS- as ,to cause them to vibratevnaturally in hrmdny with the alternations of the current v so as to produce a maximum of efficiency. The invention also involves other features of construction and details as will appear hereinafter.

Reference is to be had to the accompanying drawings, in which Fig. 1 is a front elevation of an electric bell and its operating mechanism constructed in accordance with this invention;

Fig. 2 is a sectional view on the vline 2-2 of Fig. 1, and

Fig. e",` is a plan of the operating mecha;- nismshowing the casing in section.

- The invention is shown in a form in which it involves a frame or casing 1 0. provided with a tongue 11 thereon for supporting the gong 12. This gong is mounted 'in an eccentric bushing as is usual so that 1t can be turned for adjusting purposes.

Mounted within the casing are a pair of' magnet spools vor' coils l5. These may be connected up with electric wires or cables 16 'for operation by an alternating current. Located nearthe top of the casing is a bracket 17 having a fiat shelf transverse to the axes of the `coils and provided with two integral guiding'projections 18 in a vertical plane. This is provided with a proj'ectlng tongue 19 in the plane of the shelf.

referably this tongue and also the whole bracket is made of sheet brass or other material that is nonmagnetic. Thus it constitutes a. spring for receiving the impact of the armature. l n

This tongue is provided with a perforation and the casing is provided with a perforation in alignment with it. These two perforations receive and guide an operating plunger 20 so that it moves in a direction para el with the axes of they two coils and half-way between them. Fixedly mounted with respect to the plunger is a soft iron armature 21. This is located under the tongue. Surrounding this plunger for a very large portion of its length lsa coiled spring 22. This is of comparatively heavy design and of considerable strength. The spring bears against a nut 23 which is screw threaded on the plunger so that it can be adjusted "back and forth, and a projection 26k extending do-wnfrom the armature engages the knurled or toothed edge of this nut' and acts as a lock to hold it in adjusted positions. p

In the use of the device thegong is turned and adjusted to the proper position to be engaged by the plunger when attached to cause it to sound with a maximum loudness. It is fastened in position in the usual way.

The electro-magnet at each alternation, at-

tracts 4the armature in opposition to the spring. lVhen the current changes and back toward the tongue 19. The armature, I' as will be observed, is guided by the downwardly dependin plunger is guide which it is mounted.

The purpose of the adjustment is to get guides v18 while the by they perforations in the compression of the spring exactly to the right point so that the whole structure con.- sisting of the spring, plunger and armature 'wlll vibrate in harmonywith the alternations'of the electric current. This is an important and delicate matter, for after having once secured this result the turning of the nut slightly in either direction will ver materially alter the loudness with which the gong is operated. lWith this constructionl the nut itself serves to transmit the action of the spring to the plunger. The spring bears on the nutand in itself resists the turning thereof on the plunger. However the nut can be turned by hand and it is not likely -to be turned accidently because of the pressure of the spring upon it and the lock 24 located behind it.

I am aware of the fact that in direct current operating devices for bells and the like springs have been used forV forcing the plunger in one direction fory the purpose of making or breaking a Contact. but in that case. the spring was not used as in this case for tuning purposes, and could not be. It will be observed that with this construction the simplest possible arrangement of spring is secured and no bending or twisting of it is necessary for the purpose of securing the right adjustment. v'I`he`adjustment is mechanical and exact and also permanent. IVhen in normal position with no current iowing the spring supports the arma-ture but is not under other compression, but it resists the motion of the armature toward the electro-magnets until the current is near its maximum. Also on the return stroke the spring resists' the action of the magnet on the armature until the current is near its minimum and then lifts it. This construction will operate also even when the device is turned to any other position.

Although I have illustrated and described only a single form of the invention and shown it as applied only to a bell or gong, I am well aware of the fact that modifications can be made therein and that tflie invention can be applied to other similar-*sound producing devices without departing from the scope of the invention as expressed in the claims. Therefore I do not wish to be limited to all the details of construction herein shown and described, or to the particular application of the device illustrated, but what I do claim is i 1. Ina sound producing device, the combination with an alternating current electromagnet, its armature, and a device to be vibrated, of a reciprocating plunger lixedly connected with the armature and movable therewith, a coiled spring located on said plunger for'forcing the armature away from the coils, said plunger having a. screw thread,

2. n a sound producing device, the combination of a pair of electro-magnet coils, a

guide plate located adjacent thereto and provided-with guidingpmeans in a planfe par- 4movable therewith, and a spring for moving said plunger and forcing the armature against said spring tongue when the current in the coils is in a weak condition.

3. In a sound producing device, the combination of an alternating current electro- Amagnet coil, a guide plate located adjacent thereto, and provided with guiding means in a plane parallel with the axis of said coil and having a tongue of spring metal projecting therefrom, a plunger mounted to slide in a direction parallel to the axis of the coil, an armature fixed to said plunger and movable therewith, and a coil spring encircling the plunger for forcing said armature against said spring tongue when the current in the coils is in a weak condition, the armature being forced against the action of said spring and away from said spring tongue to effect a sound producing stroke when the current in the coils is in a strong condition.

4. In a sound producingl device, the combination of an alternating current electromagnet', its armature, and a device to be vibrated, of a reciprocating plunger ixedly connected with the armature and movable therewith, a coil spring for forcing the armature away from the magnet and a guide plate having a guide4 portion for engagement with the side of the armature, and a spring tongue in th" path of movement of the armature away from said magnet.

5. In a sound producing device, the combination with a device to be vibrated, of an alternatin current electromagnet, an armature there or, a reciprocating plunger movable with the armature to strike said device during the movement of the armature toward the magnet, aV coil spring for forcing the armature away from the coils of the magnet, a. non-magnetic shock-.absorbing spring stop in position for limiting the movement of the armature away from the magnet during a weakened condition of the current strength between alternations, and means for varying the tension of said coil spring to tune the device and secure return movement of the armature and plunger against said spring stop during time intervals corresponding with the current reversals,

In testimony whereof I have hereunto se my hand.

CURT J. ROHLAND. 

